Gaseous discharge device and method of spacing the plates thereof

ABSTRACT

A pair of glass plates of a gaseous discharge display or memory device are held precisely spaced by two sets of identically sized overlapping spacer rods. The rods crisscross orthogonally within a sealed gas-containing chamber to create gaps through which the gas can flow without significant restriction between areas of the chamber separated by said rods. Sealing rods of glass having a softening temperature lower than that of the spacer rods are disposed like a border around the spacer rods and are of significantly greater diameter or height than the combined height of the two superposed sets of spacer rods. Initially the upper plate is supported solely by sealing rods; but upon heating of the assemblage, the sealing rod glass reflows, and the upper plate settles until it contacts the upper set of spacer rods; whereupon the assembly is cooled and the sealing rods fuse with the plates to create an impermeable chamber between the now precisely spaced plates.

BBQ-344+ SR 1 1111 3,808,497 was KR asaoailw 1 51 Apr 30 1974 i 1 GASEOUS DISCHARGE DEVICE AND Primary ExaminerHerman Karl Saalbach METHOD OF SPACING THE PLATES Assistant Examinerl ,awrence J. Dahl T EREOF Attorney, Agent, or Firm-Henry E. Otto, Jr., et al.

[75] Inventors: James C. Greeson, Jr., Woodstock;

Peter H. Haberland, Woodstock; [57] ABSTRACT Mi C Poughkeepsie, a" A pair of glass plates of a gaseous discharge display or f NY memory device are held precisely spaced by two sets of identically sizedoverlapping spacer rods. The rods [73] Asslgnee: Busmess Machmes crisscross orthogonally within a sealed gas-containing Corpomnon Armonk chamber to create gaps through which the gas can flow without significant restriction between areas of 22 Filed: May8, 1972 the chamber separated by said rods. Sealing rods of [21] Appl' No; 251,483 glass having a softening temperature lower than that of the spacer rods are disposed like a border around 52 1 us. Cl 313/182, 313/109.5, 313/204, the spacer rods and are of Significantly greater diame- 3 3 263 315/169 TV ter or height than the combined height of the two su- 511 Int. Cl. HOlj 1/88 p p Sets of Spacer rods- Initially the pp plate [58] Field of Search 313/1095, 182, 204, 205, is supported solely y sealing o but p heating 313 220 2 315/ 9 TV, 1 9 R of the assemblage, the sealing rod glass reflows and the upper plate settles until it contacts the upper set of spacer rods; whereupon the assembly is cooled and [56] References Cited UNITED STATES PATENTS the sealing rods fuse with the plates to create an impermeable chamber between the now precisely spaced 3.602.756 8/197] Bonnet 3 l3/l0).5 plates 3,499,!67 3/l970 Baker ct a]. 3l3/220 X 6 Claims, 4 Drawing Figures GASEOUS DISCHARGE DEVICE AND IVIETHOD OF SPACING THE PLATES THEREOF CROSS-REFERENCE TO RELATED APPLICATIONS U. S. patent application of R. Langston et al., Ser. No. 2l4, 298, filed Dec. 30, I97l, entitled Sealing Technique for Gas Panel," assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates to gas discharge display and/or memory devices, and moreparticularly to improved devices of this type embodying a method of spacing the plates with spacer elements that do not inhibit flow of gas particles between areas separated by such spacer elements.

In the above-referenced copending application of R. Langston et al., there is disclosed a gaseous discharge display device in which the superposed glass plates are accurately spaced apart using a comination of lowsoftening-point sealing rods and high-softening-point spacer rods. The large diameter sealing rods are orthogonally arranged in a window frame-like border around the significantly smaller diameter orthogonally arranged single layer of spacer rods. When the plates and rods are heated, the glass of the sealing rods reflows, causing the upper glass plate to settle gradually into contact with the high-softening-point spacer rods for accurately spacing the upper plate relative to the lower plate. When the assembly is cooled, the sealing rods fuse to the plates, creating a chamber of precise constant height into which an illuminable gasis later introduced and sealed.

This device and method are very satisfactory where the ara of the plates is relatively small and the spacer rods need only frame the display area. However, as the plate area and hence the display area are increased, spacer rods must be introduced at other intermediate locations within the chamber to maintain the critical precise spacing between the plates. In such case, the spacer rods can extend only a short distance in either direction because wherever they are present (except at the edges of the display area) they present a barrier. This barrier impedes the flow of gas particles, metastable ions, photons, etc., between adjacent areas separated by the spacer rods; and itcan also inhibit conditioning of cells, especially those immediately adjacent the spacer rods.

There is a need for a spacing arrangement that will provide accurate spacing of glass plates in gaseous discharge devices having large display areas requiring spacers at various places within the display area as well as around the periphery thereof. It would also be desirable to minimize the size ofthe spacer elements for aesthetic reasonsso they will not be visible and mar the display area, and at the same time provide greater latitude in their location.

' SUMMARY OF THE INVENTION method, the plates are held precisely spaced at a preselected constant distance by two sets of identically sized crisscrossing spacer rods disposed orthogonally with respect to each other in overlapping lattice-like contact within the sealed gas-containing chamber. The spacer rods of one set contact the dielectric coating over the parallel conductors on one of the plates; and the spacer rods of the other set contact the dielectric coating over the orthogonally arrangedparallel conductors on the other plate. Since these spacer rods have diameters equal to only one-half of said preselected constant distance, flow of gas particles between areas separated by the spacer rods is not significantly impeded. The spacer rods associated with the conductors on each plate are disposed between, and extend parallel to, the conductors on that particular plate. The diameters of the spacer rods preferably vary between approximately 0.002 inch and 0.0037 inch, according to which of the embodiments, hereinafter described, is employed.

Other objects and advantages will become apparent from the following more detailed description of the invention and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 4 is a fragmentary sectional view, similar to FIG.

2, but showing an alternate embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT The gaseous discharge display and/or memory device constructed according to this embodiment and illustrated in FIGS. 1-3 comprises, briefly, an upper glass plate 10 and a lower glass plate 11, each including substrates 12,13, respectively, on the facing-surfaces of which are formed passivated metalized conductor arrays 14,15, respectively. As illustrated, the arrays 14,15 each compriserespective pluralities of parallel conductors, the conductors of array 14 being disposed orthogonally relative to those of array 15. The ends of the array on each plate extend beyond the edges of the other plate to facilitate connection to alternate conductors of the array, in conventional manner. As best shown in FIGS. 2,3, the conductors of each array 14,15 are overlaid with respective transparent dielectric coatings 16,17, preferably of glass, which provide flat surfaces 18,19, respectively.

The plates 10,11 are fused into an integrated structure in the following-manner. Unfused, heat-fusible sealing material, preferably in the form of rods 20 of low-softening-point glass, are placed in a window- I frame border-like pattern on surface 19 of lower plate Toward this end, and according to the invention, ap-

11. These rods 20 are of an identical diameter that is significantly greater than the precise preselected dis-' tance at which these plates are ultimately to be joined. According to the invention, two sets of identically sized upper and lower spacer rods 21,22 are then placed in overlaying relation in a two-stratum crisscross pattern within the border. The lower rods 22 extend parallel to, and are equidistantly spaced between, adjacent pairs of conductors in array 15 and rest on flat surface 19; whereas upper rods 21 overlay and rest on lower rods 22 in a predetermined lateral spacing hereinafter to be described. As will be noted from FIG. 3, the combined height of the overlapped rods21,22 is substantially less than the diameter of the sealing rods 20.

The upper plate 10 is now positioned over the lower plate 11 with upper plate surface 18 contacting sealing rods 20 and transversely positioned such that the upper spacer rods 21 extend parallel to, and equidistant from, but substantially below, pairs of adjacent conductors of array 14 (as a result of the aforesaid predetermined spacing of rods 21 on rods 22). Rods 21,22, which are preferably formed of glass, have a significantly higher softening point than that of the sealing rods. Hence, when the unfused assemblage of discrete parts is thereafter heated in a vacuum oven to a temperature sufficient cause melting and reflow of the sealing material of rods 20, upper plate will gradually settle from the position shown in FIG. 3 until surface 18 contacts upper spacer rods 21, as shown in FIG. 2.

The assemblage is now permitted to cool, causing the now reflowed sealing material, designated in FIG. 2, to fuse to the surfaces 18,19 of the respective dielectric layers 16,17 and thereby fuse plates 11 into an integrated structure having an impermeable chamber 23 sealed about its periphery by the material 20'. In accordance with conventional practice, this chamber 23 is now evacuated via anexhaust tube 24 (FIG. I), then charged with an illuminable gas at appropriateprcssure; whereupon the tube is sealed to permanently en trap the gas within the chamber.

It will thus be seen that according to a feature of the invention, the plates will be maintained at a precise preselected distance by the crisscross pattern of overlapping spaccr rods 21,22. Because these spacer rods have a diameter which is equal to only one-half of the totalconstant space between the surfaces 18,19, the gas particles, metastable ions, protons, etc., may flow without significant restriction between the various areas into which the chamber 23 is separated by the lattice arrangement of spacer rods.

In the preferred embodiment illustrated in FIG. 2, the sealing rods 20'preferably havea diameter of about 0.040 inch, and the spacer rods 21,22 preferably have a diameter of approximately 0.002 inch; and dielectric coatings 16,17 have a softening temperature which is above the temperature to which the assemblage is subjected during the above-described fusing operation so that the rods 21,22 will-contact, but not penetrate, the dielectric surfaces18,19. With this arrangement, the small size of the spacer rods renders them substantially indistinguishable from the glass plates and hence is aesthetically desirable. Also, blocking of the display area at the crossover points of the respective rods 21,22 is minimized by spacing these rods between conductors so as not to blank out any appreciable illumination upon firing of cells comprised of conductors adjacent to these rods.

DESCRIPTION OF ALTERNATE EMBODIMENT The device and sealing method employed according to this embodiment (see FIG. 4) are identical with those already described in connection withth'e embodiment of FIGS. 1-3, except in the following respects:

According to the instant embodiment, the upper and lower spacing rods 2l',22', respectively, are of somewhat larger diameter, such as 0.0037 inch; and the coatings l6',l7 are of a dielectric having a softening temperature which is below the temperature to which the assemblage is heated during the fusing process. As

a result, the spacer rods 21,22 will penetrate the di-- electric coatings until they contact the surfaces of the respective substrates 12,13. Thus the constant spacing between the plates will be defined by respective contacts of the spacer rods 21,22' with the substrates rather than with the dielectric coatings; however, the actual constant height of the chamber 23 will still be that corresponding to the precisely fixed spacing between the flat portions of surfaces 18',19'.

It is to be understood that the conductor configuration and composition, the specific oven structure and temperatures used for the fusing operation, and the apparatus by which the chamber 23 is evacuated and then charged with illuminable gas may be as taught in the prior art, such as the above-referenced Langston et al. application; and hence they have not been described here in any more detail than is necessary for an understanding of the present invention.

While the invention has been shown and described with reference to preferred embodiments thereof, it will be understood that various substitutions and changes in form and detail may be made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, the gas discharge display and/or memory device herein disclosed and the method of making same are to be considered merely as illustrative, and the scope of the invention is to be limitedonly as specified in the claims.

What is claimed is: l. A gaseous discharge display device comprising a pair of glass plates each including substrates on which are provided parallel conductors overlaid with a dielectric coating to present a flat surface,

means including a frame-like border of lowsoftening-point sealing material sealing said plates in superposed spaced parallel relation, with said surfaces adjacent, to provide within the border a sealed chamber containing an illuminable gas, the conductors on each plate being orthogonal to those on the other plate, and

spacer means for-maintaining said surfaces precisely spaced at a preselected constant distance,

said spacer means comprising two sets of spacer elements of identical height disposed orthogonally with respect to each other in overlapping latticelike contact within the chamber, with all elements of each respective set contacting only a corresponding respective one of said surfaces, whereby the gas may flow either over or under the elements or around the crossover points thereof without significant restriction to substantially all areas of said sealed chamber separated by said spacer elements.

2. The device according to claim 1, wherein the respective spacer elements that contact each surface are disposed parallel to conductors that are overlaid by such surface.

3. The device according to claim 1, wherein at least one of the spacer elements that contacts said surface of one of said plates is disposed substantially equidistant between, and extends parallel to, a pair conductors on said one plate, and

at least one of the spacer elements that contacts the said surface of the other of said plates is disposed substantially equidistant between, and extends parallel to, a pair of adjacent conductors on said other plate. 4. The device according to claim 1, wherein said spacer elements are rods of glass having a softening point higher than that of said sealing means, and said rods rest on and do not significantly penetrate one of said flat surfaces. '5. The device according to claim 1, wherein of adjacent said spacer elements are rods of glass having a softening point higher than that of said sealing means and higher than that of the dielectric coating, and

said rods penetrate said dielectric coating and contact the substrate but project beyond the level of said surface to make said lattice-like overlapping space-defining contact with each other.

6. The device according to claim 1, wherein said constant distance is approximately 0.004 inch to 0.006 inch, and each respective set of spacer elements extends sufficiently from the surface it'contacts, to provide one-half of said distance. 

1. A gaseous discharge display device comprising a pair of glass plates each including substrates on which are provided parallel conductors overlaid with a dielectric coating to present a flat surface, means including a frame-like border of low-softening-point sealing material sealing said plates in superposed spaced parallel relation, with said surfaces adjacent, to provide within the border a sealed chamber containing an illuminable gas, the conductors on each plate being orthogonal to those on the other plate, and spacer means for maintaining said surfaces precisely spaced at a preselected constant distance, said spacer means comprising two sets of spacer elements of identical height disposed orthogonally with respect to each other in overlapping lattice-like contact within the chamber, with all elements of each respective set contacting only a corresponding respective one of said surfaces, whereby the gas may flow either over or under the elements or around the crossover points thereof without significant restriction to substantially all areas of said sealed chamber separated by said spacer elements.
 2. The device according to claim 1, wherein the respective spacer elements that contact each surface are disposed parallel to conductors that are overlaid by such surface.
 3. The device according to claim 1, wherein at least one of the spacer elements that contacts said surface of one of said plates is disposed substantially equidistant between, and extends parallel to, a pair of adjacent conductors on said one plate, and at least one of the spacer elements that contacts the said surface of the other of said plates is disposed substantially equidistant between, and extends parallel to, a pair of adjacent conductors on said other plate.
 4. The device according to claim 1, wherein said spacer elements are rods of glass having a softening point higher than that of said sealing means, and said rods rest on and do not significantly penetrate one of said flat surfaces.
 5. The device according to claim 1, wherein said spacer elements are rods of glass having a softening point higher than that of said sealing means and higher than that of the dielectric coating, and said rods penetrate said dielectric coating and contact the substrate but project beyond the level of said surface to make said lattice-like overlapping space-defining contact with each other.
 6. The device according to claim 1, wherein said constant distance is approximately 0.004 inch to 0.006 inch, and each respective set of spacer elements extends sufficiently, from the surface it contactS, to provide one-half of said distance. 